The default for the aggfunc parameter is actually the mean

passenger_class_fares = titanic_survival.pivot_table(index="pclass", values="fare", aggfunc=numpy.mean)

passenger_survival = titanic_survival.pivot_table(index="pclass", values="survived") 

passenger_age = titanic_survival.pivot_table(index="pclass", values="age")

print(passenger_class_fares)
print(passenger_survival)
print(passenger_age)

import numpy as np

port_stats = titanic_survival.pivot_table(index="embarked", values=["fare","survived"], aggfunc=numpy.sum)

print(port_stats)

Drop all rows in titanic_survival where the columns age or sex have missing values

new_titanic_survival = titanic_survival.dropna(axis=0,subset=["age", "sex"])